<!DOCTYPE html>
<html lang="en">

<head>
  <meta charset="UTF-8">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <meta http-equiv="X-UA-Compatible" content="ie=edge">
  <script src="https://cdn.staticfile.org/react/16.4.0/umd/react.development.js"></script>
  <script src="https://cdn.staticfile.org/react-dom/16.4.0/umd/react-dom.development.js"></script>
  <script src="https://cdn.staticfile.org/babel-standalone/6.26.0/babel.min.js"></script>
  <title>Document</title>
  
</head>

<body>
  <div id="render"></div>
  <script type="text/babel">
    class Clock extends React.Component {
      constructor() {
        super()
        this.state = { isLogin: false }
        this.changeLogin = this.changeLogin.bind(this)
      }
      changeLogin() {
        this.setState(res => ({
          isLogin: !res.isLogin
        }))
      }
      render() {
        let login = this.state.isLogin
        let button
        if (login) {
          button = <div> <h1>欢迎回来</h1><button onClick={this.changeLogin}>退出</button></div>
        } else {
          button = <div> <h1>请先注册登录</h1><button onClick={this.changeLogin}>登录</button></div>
        }
        return button
      }
    }

    ReactDOM.render(
      <Clock />,
      document.getElementById("render")
    )


  </script>

</body>

</html>